1. Field of the Invention
The present invention relates to a speech processing apparatus and method.
2. Description of the Related Art
Speech synthesis methods include a recorded-speech-playback method and a text-to-speech method. Recorded-speech-playback synthesizes speech by connecting recorded words and phrases. Recorded-speech-playback provides high speech quality but can only be used for repetitive sentences. Text-to-speech analyzes an input sentence and converts it into speech. This technique may receive pronunciations and phonetic symbols instead of sentences. Text-to-speech can be used for all kinds of sentences but is inferior in speech quality to recorded-speech-playback and is not free from reading errors.
Conventionally, some speech processing apparatus designed to output guidance speech by speech synthesis uses a method using both recorded-speech-playback and text-to-speech (Japanese Patent Laid-Open No. 9-97094).
According to the above conventional technique, however, frequently changing recorded-speech-playback and text-to-speech in one piece of guidance speech will make it difficult to hear the guidance due to the difference in speech quality between the two techniques.